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Williamson County, TX Water Quality

Water quality data for 16 public water systems serving Williamson County, Texas — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 16 water systems · 18 cities
✅
Generally Safe — Most Systems Performing Well

The majority of water systems have no active violations and lead levels well below the federal action level.

B

Williamson County Earns a B

Williamson County: 18 communities across 16 water systems. 77.8% have no open violations.

  • Median lead where detected: 2.22 ppb
  • 16 communities with a lead detection, 2 reporting none detected
  • 1 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 77.8% of communities have no open violations
2.22 ppb
Median Lead Level
County-wide, 90th percentile
16
Water Systems
Active CWS & NTNCWS
77%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Leander
    1.10 ppb
    No federal limits exceeded on record
    A
  • Granger
    3.95 ppb
    No federal limits exceeded on record
    B
  • Jarrell
    Not detected
    No federal limits exceeded on record
    A
  • Cedar Park
    3.95 ppb
    1 health-based violation since 2015
    A
  • Hutto
    Not detected
    1 health-based violation since 2015
    A
⚠ Needs Attention
  • Coupland
    1.41 ppb
    PFAS above the limit at 3 of 9 sampling points
    D
  • Bartlett
    2.73 ppb
    2 violations currently open
    D
  • Georgetown
    2.23 ppb
    1 violation currently open
    C
  • Santa Rita Ranch
    2.23 ppb
    1 violation currently open
    C
  • Serenada
    2.23 ppb
    1 violation currently open
    C
County Lead Level — Median 2.22 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 2.22 ppb — 14.8% of the federal action level
Systems by Lead Level
Under 5 ppb
15
5 – 10 ppb
1
No Data
2

All Cities in Williamson County

Round Rock 5.05 ppb A
Cedar Park 3.95 ppb A
Georgetown 2.23 ppb C
Leander 1.10 ppb A
Hutto Not detected A
Taylor 1.93 ppb A
Brushy Creek 1.28 ppb A
Sonterra 0.43 ppb A
Santa Rita Ranch 2.23 ppb C
Liberty Hill 2.11 ppb B
Serenada 2.23 ppb C
Bartlett 2.73 ppb D
Granger 3.95 ppb B
Florence 2.21 ppb B
Jarrell Not detected A
Thrall 1.33 ppb B
Coupland 1.41 ppb D
Weir 2.50 ppb B
Showing 18 cities
No active violations Active violations

About Williamson County Drinking Water

Williamson County is served by 16 water systems covering 18 communities. 78% have no open violations.

Of the communities reporting lead results, 16 recorded a detection, with a median of 2.22 ppb — 15% of the federal action level. 2 reported none detected, which means below the laboratory limit rather than an absence of lead.

1 of 18 communities have PFAS above the limits EPA set in 2024, measured as a running annual average at each sampling point. State inspectors recorded no significant deficiencies.

Frequently Asked Questions

Is Williamson County tap water safe to drink?▼
78% of communities have no open violation. 1 of 18 have PFAS above the federal limit, which is the main open concern.
What is the lead level in Williamson County?▼
Among communities with a detection the median is 2.22 ppb, 15% of the 15 ppb action level. 2 reported none detected and 0 reported no result.
How many water systems serve Williamson County?▼
16 community water systems serve 18 communities here.
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